Some transportable mixers, such as concrete mixers, typically employ a plurality of chute sections which are hinged together for movement between a retracted transport position and an extended discharge position. After transport to a site, the chute sections are extended to direct discharge of the concrete mix as desired. Manytimes the entire chute assembly is also mounted for pivotal movement over a lateral arc for further control over discharge of the mix.
Various assemblies have been utilized for retracting and extending such chutes between these positions. Devices representative of the prior art are shown in U.S. Pat. Nos. 3,774,741, 3,456,769, 3,930,567 and 4,054,194. The devices of these prior patents include a substantial number of parts in the actuator assemblies for positioning the hinged chute sections between such positions. It will be appreciated that such chutes are heavy, applying large stresses to such chute actuator assemblies. These actuator assemblies thus tend to wear out under rough handling and, due to their configurations, hardened cement tends to build up on the chute actuator assemblies of the prior art.
Certain prior actuator assemblies such as that disclosed in U.S. Pat. No. 3,456,769, employ hydraulic or pneumatic drive means for actuating movement of the chute sections between the retracted and discharge positions, but leave the piston rods exposed to damage in the extended discharge position such that the rods are exposed to hardened concrete. The hydraulic or pneumatic actuators of the prior art connect to a multiplicity of various devices for moving one chute relative to the other under the influence of the hydraulic or pneumatic piston actuator or to move the chute sections between the retracted and discharge positions.
Mechanical gear arrangements have also been suggested in the prior art, which are subject to the same disadvantages of the other type of actuators and connecting assemblies for pivoting the chute sections between said positions. Such gear arrangements likewise, are subjected to similar wear and exposure to damage. In some cases, the terminal chute section is suggested in the prior art to be manually pivoted and nested with the next adjacent chute section.
It is also taught in the prior art that various means can be provided to pivot the entire chute about a generally vertical axis, either manually or mechanically, in order to facilitate discharge of the concrete within certain desired boundaries. The prior mechanisms employed for such positioning of the chute sections have also included a multiplicity of parts subject to the same disadvantages above noted with respect to retraction and extension of the chute sections.
There is thus a need for improved linkage assemblies for extension/retraction of the chute sections and for traversing the chute assembly about an upright axis, which affords better protection for the linkage and actuator thereof.